This may be a bit of far-fetched pipe dream, but Mozilla could use a new edge in the current age of browser technology. This idea is basically to create an in-browser Notion-alternative around open or saved web URLs, possibly with some graph view (a la Cotoami/Obsidian/etc.) which probably sounds crazy but hear me out.
Individuals and organizations are growing out of web-based office tools that rigidly define types of "files" and instead moving towards powerful and intuitive everything-workspace platforms like Notion and Airtable. With the address bar in Firefox auto-completing to suggest tabs open elsewhere alongside bookmarks, and features/plugins like Tree Style Tabs, and Tab Grouping, and Multi-Acconut Containers, the functionality of simple Bookmarks has a lot of overlap with "open" tabs and one day the distinction might disappear.
I'm envisioning a "workspace" view, which by default might just lay out all your bookmarks and tabs as thumbnails grouped by tab-group or folder, but which can be arbitrarily rearranged, annotated, combined with notes (rip), and shared or published in something akin to a mix of social bookmarking, wiki, or inspiration/interest boards with optional integration with some sort of social media platform *cough cough* Pocket *cough*
Maybe this could even be an avenue for monetization as organizations could want to pay to have this hosted with access restricted to company email addresses.